The present invention is directed to a method which employs infrared radiation to effect the cure of a desiccant filled silicone composition in a rigid or semi-rigid spacer for a multi-pane sealed window.
Chenel, U.S. Pat. Nos. 4,226,063 and 4,205,104, shows multi-pane sealed windows having a silicone and butyl rubber as flexible spacer sealing elements. In U.S. Pat. No. 4,622,249, similar materials are used as spacers. However, the butyl rubber is used as the outer sealant and a desiccant filled silicone sealant is employed as the inner spacer. In U.S. Pat. No. 5,007,217, an inner spacer is made from a moisture permeable flexible or semi-rigid foam material which incorporates a desiccant material. In many situations, a more rigid material is preferred as the spacer, because the glazing unit often incorporates a heat shrinkable plastic film which can be applied in a final assembly step. Sufficient spacer rigidity often is needed to prevent wrinkles from being formed at the corners following heat shrinking of the plastic film.
Because of its rigidity, steel is often preferred as the spacer for multi-pane window applications. In addition, dehydrated zeolites, which are derived from hydrated aluminum and calcium or sodium silicates have gained wide acceptance as desiccants. In one design, the desiccant is used directly in a steel tubular spacer having perforated walls. Moisture uptake is achieved through the walls of the spacer when in place. Because the desiccant is sometimes incorporated at the terminus of the spacer, it can be difficult to incorporate the desiccant in an economic manner.
Preferably, the spacer has a readily accessible U-shaped or V-shaped open channel. However, in order to minimize loss of the desiccant through spillage, a heat curable desiccant binder is often needed which allows the mixture to remain stable and flowable for at least 60 minutes below about 50.degree. C. In addition, the resulting cured product must be adherent to the spacer wall, while maintaining its moisture absorbing capability once it is installed in the multi-pane window structure.